1. Field
The present invention generally relates to the transmission of data over telecommunication networks, and to telecommunication devices that enable such transmission. More particularly, the invention concerns a new technique for maintaining synchronization with a telecommunication device in a half-duplex mode for a low duty cycle data transmission operation.
2. Background
Remote monitoring of operations may involve remotely-situated, battery-operated, wireless telecommunication devices that capture operational status information and transmit via radio frequency signals the operational status information to a centrally-situated information-processing device. Oftentimes, the operational status information can be transmitted via radio frequency signals as short messages. In such remote monitoring and transmission applications, issues associated with power consumption management are an important concern.
In a typical operational environment, battery-operated monitoring and telecommunication devices are desirable to facilitate operating efficiency and to reduce maintenance costs. Implementation efficiency is improved because batteries obviate arrangements for an external power source and enable deployment of self-contained units that are easily installed at a variety of sites. Maintenance costs are reduced because the unit lacks dependence on external power sources and because a faulty unit is easily replaced by another. To optimize these advantages, it is most desirable for the monitoring and telecommunication device to operate for an extended period of time without requiring battery replacement or the like.
One way to extend the life of a battery is to reduce the load demanded of it. For example, a remotely-situated telecommunication device may be configured to operate according to a reduced duty cycle, where it is placed in a sleep or low-power operational mode when there are no ongoing communications with, for example, a centrally-situated information-processing device. This usually requires that a trade-off be made between the availability of the battery-powered telecommunication device for communications with the information-processing device and the amount of achievable reduction in power consumption. However, a remote telecommunication device employing such a power consumption saving technique may not be able to communicate optimally with a centrally-situated information-processing device because all or part of its communication circuitry is shut down when the device is in sleep mode to conserve battery power. That is, communication by the remote device is available only on an occasional basis.
There is therefore a need in the art for means of synchronizing the exchange of information between a remotely-situated monitoring and transmission device configured to operate according to a low duty cycle, and a centrally-situated information-processing device with which it is in communication.